Australian Spotted Mackerel fish identification, its habitats, characteristics, fishing methods.
The Australian spotted mackerel is an iridescent blue green color on the upper back and flanks becoming silvery on the sides with a silvery white belly area. A broad row of dark spots run along the body from just behind head to the tail. Specimens have been recorded at up to 104 cm in length, and weighing up to 10.2 kg. It is found in the western Pacific, along the northern coast of Australia. It feeds largely on fishes, particularly anchovies and sardines, with smaller quantities of shrimps and squids. It is sometimes confused with Japanese Spanish mackerel, Scomberomorus niphonius.
The Australian spotted mackerel, Scomberomorus munroi, is a species of fish in the family Scombridae, also known as Spotty Mackerel and Spotty, is found in the western Pacific: restricted to the northern coast of Australia, from the Abrolhos Islands region of Western Australia to Coffs Harbor and Kempsey in central New South Wales; also occurring in southern Papua New Guinea from Kerema to Port Moresby.
Spotted Mackerel have an elongated body with pointed noses, but without the pectoral corslet of the tunny. Large mouth full of teeth; the teeth are large, compressed, and sharp, short, and even on the palate bones. There is an elevated crest on each side of the tail, and a smaller one above and below it. They have a light silvery grey body that is blue green above the lateral line. Lateral line gradually curving down toward caudal peduncle. Intestine with 2 folds and 3 limbs. The rays of the first dorsal fin project beyond the membrane; the second dorsal fin is triangular, emarginated behind; there are eight or nine finlets between the caudal and the second dorsal and the anal. Interpelvic process small and bifid. Swim bladder absent. Body covered with small scales. Common fork length ranges between 50 to 80 cm. Spotted Mackerel can grow to about a meter and around 8 kg in weight however common in the 1.5-4kg range.
Distinguishing characteristics: Several, 20 or more, poorly defined rows of spots on sides (larger than the pupil but smaller than the eye) on light silver-grey body.
20–22 Dorsal spines with 17-20 soft rays.
17–19 Anal soft rays.
Max. length: 104 cm.
Max. weight: 10.2 kg.
The color above is dark leaden, lighter on the sides; the jaws, gill covers, cheeks and belly are silvery white, with a satin lustre; the dorsal ridge dark green. There are 20 or more circular or oblong spots on the sides above and below the lateral line, most of them above the line and anterior to the second dorsal. The membrane of the first dorsal fin is entirely black (bright steely blue when fresh), the second leaden. The inner surface of the pectoral fin is dark blue and light above. The anal fin and anal finlets are light silvery gray. There are blotches of white toward bases of more posterior membranes in some specimens.
They are often confused with the Queensland School Mackerel, however can be distinguished by the blotches on the School Mackerel are poorly defined and less than the Spotted Mackerel, also the first dorsal fin of the School Mackerel is jet black with a large contrasting white section between the sixth and seventh spine which the spotted Mackerel does not have. Also Spotted Mackerel have first dorsal fin with 20-22 spines and inner surface of pectoral fin is dark blue.
Spotted Mackerel, like most other species of Scomberomorus, has two loops and three limbs to the intestine. It has more vertebrae (50-52) than Japanese Spanish mackerel (Scomberomorus niphonius) (48-50) and most other species of Australian Scomberomorus (Narrow-barred Spanish mackerel, Scomberomorus commerson 42-46, Queensland school mackerel, Scomberomorus queenslandicus 48-49, Broadbarred king mackerel, Scomberomorus semifasciatus 44-46), except for Papuan seerfish, Scomberomorus multiradiatus from Papua New Guinea (55-56). Spotted Mackerel has a deeper body and a longer postorbital distance than Japanese Spanish mackerel.
Spotted Mackerel are pelagic, oceanodromous species, and found more commonly in offshore, open waters away from reefs and shoals. They also venture into bays and estuaries. It forms large schools which move close inshore along the coast of Queensland, where it is commonly taken between December and April or May. However they also found sometimes in northern New South Wales and across the top of Australia right around to Northern Western Australia. Spotted Mackerel move long distances, over 100 km from the release site. The longest movement was 1,100 km over 228 days. These movements, together with spatial and temporal patterns of tagging effort and commercial fishing harvest, indicate a single eastern stock that undertakes a seasonal migration associated with spawning and feeding along the Queensland and New South Wales coasts
Spotted Mackerel feed almost exclusively on pelagic species such as anchovies, pilchards, herring and sardines with smaller quantities of shrimps and squids.
Female and male Spotted Mackerel reach sexual maturity at about 60 cm and 52 cm length, respectively, at about 1–2 years of age. Females are larger than males. Spawning occurs in offshore waters from late winter to early spring and this coincides with reduced feeding activity. Spotted Mackerel spawn between August and October in northern Queensland waters with peak spawning occurring in September. Spawning times tend to be associated with higher water temperatures that promote optimal food availability for the rapid growth and development of the larvae.
After spawning pelagic eggs and larvae may then be dispersed southwards by the East Australian Current. Eggs have a large oil droplet that aids in buoyancy and keeps them at the top of the water column which is warmer, well oxygenated and has an abundant planktonic food supply for the larvae once they are hatched. As the young larvae grow they move from the offshore spawning grounds to inshore and estuarine habitats where they are frequently found in the juvenile phase of their growth cycle. In the inshore environment they feed mostly on the larvae and juveniles of small fish and crustaceans until they become large enough to tackle small fish and squid.
They grow quickly for the first 3 years of life, after which growth slows. They demonstrate sex-specific growth rates, with females tending to grow faster and to larger sizes. Spotted Mackerel have been found aged up to seven years and up to 105 cm total length and 7.4 kg.
Spotted Mackerel are great fun to catch and are excellent for the table; they are great fighters and great tasting when eaten fresh. Mackerel readily take trolled lures of minnow, feather jigs, metal lures and skirted lures. Live baits are another excellent way to catch it. Mackerel can become a common catch when reef fishing by 'floating' an unweighted pilchard or live bait out the back of the boat while bottom bouncing. . If you’re going to use soft plastics, be warned that mackerel are toothy and may make short work of your lure. Often unweighted baits will be effective as they waft naturally in the burley trail.
Spotted Mackerel prefer small bait and trolling half pilchards or other small fish can be very productive. One of the most effective ways to target mackerel is by trolling. They can also sometimes be seen schooling under diving birds where casting small metal lures retrieved quite quickly can be productive. Concentrate your trolling on bait rich areas and try to match your lure or bait to what the fish are feeding on. Deep diving hard bodied minnows are extremely effective while shallow and mid range divers will also work well depending on the conditions and where the fish are holding. Live baits account for a great strike rate when they’re available but carefully rigged dead baits will also do the trick. Baits such as gar, wolf herring, and pilchard can all work effectively.
Arguably the most fun way to target Spotted Mackerel is using metal lures. Also known as slugs or chromies, metal lures are designed to imitate a fleeing bait fish. Once you’ve located a school of bait on the surface, approach to within casting range and launch your metal lure into the frenzy and retrieve it at high speed. Mackerel will typically nail your lure on the retrieve and the fun begins! Jigging similar lures or knife jigs is also a great way of catching mackerel. Drop your jig down into mid water schools of bait and violently lift and rod tip up and down. Make sure you wind any slack line as you drop the rod tip.